Although intra-luminal ultrasound scanning has been developed with some degree of success for the imaging of the cardiovascular system, the circular side scanning geometry of the catheter ultrasound transducer is intrinsically unsuitable for many diagnostic applications. The objective of this application is the improvement of real time intra-luminal scanning via the development of a new generation of miniature forward looking mechanical sector scanners incorporating high frequency transducers above 20 MHz to enable improved guidance of cardiac interventional procedures. Each piezoelectric transducer is driven by a tiny linear actuator operating electrostatic forces combined with pivoting hinges to produce a sector scan. The linear actuator is an example of a microelectromechanical system (MEMS), now one of the most important research fields of microelectronics. The transducer / MEMS assembly will be totally housed within a cardiac catheter. Applications may include: 1) real time intra-luminal sector scanning of the heart at 20-40 MHz; 2) real time intra-vascular sector scanning at 20-50 MHz; 3) real time intra-luminal volumetric scanning; 4) the combination of cardiac intra- ventricular ultrasound imaging with electrophysiological endocardial mapping; 5) the combination of intra-luminal ultrasound imaging and intra-luminal radio-frequency or ultrasound thermal ablation.